1 /*
2 * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
153 */
154 public class Throwable implements Serializable {
155 /** use serialVersionUID from JDK 1.0.2 for interoperability */
156 private static final long serialVersionUID = -3042686055658047285L;
157
158 /**
159 * Native code saves some indication of the stack backtrace in this slot.
160 */
161 private transient Object backtrace;
162
163 /**
164 * Specific details about the Throwable. For example, for
165 * {@code FileNotFoundException}, this contains the name of
166 * the file that could not be found.
167 *
168 * @serial
169 */
170 private String detailMessage;
171
172 /**
173 * The throwable that caused this throwable to get thrown, or null if this
174 * throwable was not caused by another throwable, or if the causative
175 * throwable is unknown. If this field is equal to this throwable itself,
176 * it indicates that the cause of this throwable has not yet been
177 * initialized.
178 *
179 * @serial
180 * @since 1.4
181 */
182 private Throwable cause = this;
183
184 /**
185 * The stack trace, as returned by {@link #getStackTrace()}.
186 *
187 * @serial
188 * @since 1.4
189 */
190 private StackTraceElement[] stackTrace;
191 /*
192 * This field is lazily initialized on first use or serialization and
193 * nulled out when fillInStackTrace is called.
194 */
195
196 /**
197 * The list of suppressed exceptions, as returned by
198 * {@link #getSuppressedExceptions()}.
199 *
200 * @serial
201 * @since 1.7
202 */
203 private List<Throwable> suppressedExceptions = null;
204 /*
205 * This field is lazily initialized when the first suppressed
206 * exception is added.
207 *
208 * OutOfMemoryError is preallocated in the VM for better OOM
209 * diagnosability during VM initialization. Constructor can't
210 * be not invoked. If a new field to be added in the future must
211 * be initialized to non-null, it requires a synchronized VM change.
212 */
213
214 /** Message for trying to suppress a null exception. */
215 private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception.";
216
217 /** Caption for labeling causative exception stack traces */
218 private static final String CAUSE_CAPTION = "Caused by: ";
219
220 /** Caption for labeling suppressed exception stack traces */
221 private static final String SUPPRESSED_CAPTION = "Suppressed: ";
222
223 /**
224 * Constructs a new throwable with {@code null} as its detail message.
225 * The cause is not initialized, and may subsequently be initialized by a
226 * call to {@link #initCause}.
227 *
228 * <p>The {@link #fillInStackTrace()} method is called to initialize
229 * the stack trace data in the newly created throwable.
230 */
231 public Throwable() {
232 fillInStackTrace();
233 }
234
235 /**
236 * Constructs a new throwable with the specified detail message. The
555 */
556 public void printStackTrace(PrintStream s) {
557 printStackTrace(new WrappedPrintStream(s));
558 }
559
560 private void printStackTrace(PrintStreamOrWriter s) {
561 // Guard against malicious overrides of Throwable.equals by
562 // using a Set with identity equality semantics.
563 Set<Throwable> dejaVu =
564 Collections.newSetFromMap(new IdentityHashMap<Throwable, Boolean>());
565 dejaVu.add(this);
566
567 synchronized (s.lock()) {
568 // Print our stack trace
569 s.println(this);
570 StackTraceElement[] trace = getOurStackTrace();
571 for (StackTraceElement traceElement : trace)
572 s.println("\tat " + traceElement);
573
574 // Print suppressed exceptions, if any
575 for (Throwable se : getSuppressedExceptions())
576 se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, "\t", dejaVu);
577
578 // Print cause, if any
579 Throwable ourCause = getCause();
580 if (ourCause != null)
581 ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, "", dejaVu);
582 }
583 }
584
585 /**
586 * Print our stack trace as an enclosed exception for the specified
587 * stack trace.
588 */
589 private void printEnclosedStackTrace(PrintStreamOrWriter s,
590 StackTraceElement[] enclosingTrace,
591 String caption,
592 String prefix,
593 Set<Throwable> dejaVu) {
594 assert Thread.holdsLock(s.lock());
595 if (dejaVu.contains(this)) {
596 s.println("\t[CIRCULAR REFERENCE:" + this + "]");
597 } else {
598 dejaVu.add(this);
599 // Compute number of frames in common between this and enclosing trace
600 StackTraceElement[] trace = getOurStackTrace();
601 int m = trace.length - 1;
602 int n = enclosingTrace.length - 1;
603 while (m >= 0 && n >=0 && trace[m].equals(enclosingTrace[n])) {
604 m--; n--;
605 }
606 int framesInCommon = trace.length - 1 - m;
607
608 // Print our stack trace
609 s.println(prefix + caption + this);
610 for (int i = 0; i <= m; i++)
611 s.println(prefix + "\tat " + trace[i]);
612 if (framesInCommon != 0)
613 s.println(prefix + "\t... " + framesInCommon + " more");
614
615 // Print suppressed exceptions, if any
616 for (Throwable se : getSuppressedExceptions())
617 se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION,
618 prefix +"\t", dejaVu);
619
620 // Print cause, if any
621 Throwable ourCause = getCause();
622 if (ourCause != null)
623 ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, prefix, dejaVu);
624 }
625 }
626
627 /**
628 * Prints this throwable and its backtrace to the specified
629 * print writer.
630 *
631 * @param s {@code PrintWriter} to use for output
632 * @since JDK1.1
633 */
634 public void printStackTrace(PrintWriter s) {
635 printStackTrace(new WrappedPrintWriter(s));
636 }
763
764 /**
765 * Returns the number of elements in the stack trace (or 0 if the stack
766 * trace is unavailable).
767 *
768 * package-protection for use by SharedSecrets.
769 */
770 native int getStackTraceDepth();
771
772 /**
773 * Returns the specified element of the stack trace.
774 *
775 * package-protection for use by SharedSecrets.
776 *
777 * @param index index of the element to return.
778 * @throws IndexOutOfBoundsException if {@code index < 0 ||
779 * index >= getStackTraceDepth() }
780 */
781 native StackTraceElement getStackTraceElement(int index);
782
783 private void readObject(ObjectInputStream s)
784 throws IOException, ClassNotFoundException {
785 s.defaultReadObject(); // read in all fields
786 List<Throwable> suppressed = null;
787 if (suppressedExceptions != null &&
788 !suppressedExceptions.isEmpty()) { // Copy Throwables to new list
789 suppressed = new ArrayList<Throwable>();
790 for (Throwable t : suppressedExceptions) {
791 if (t == null)
792 throw new NullPointerException(NULL_CAUSE_MESSAGE);
793 suppressed.add(t);
794 }
795 }
796 suppressedExceptions = suppressed;
797 }
798
799 private synchronized void writeObject(ObjectOutputStream s)
800 throws IOException
801 {
802 getOurStackTrace(); // Ensure that stackTrace field is initialized.
803 s.defaultWriteObject();
804 }
805
806 /**
807 * Adds the specified exception to the list of exceptions that
808 * were suppressed, typically by the {@code try}-with-resources
809 * statement, in order to deliver this exception.
810 *
811 * <p>Note that when one exception {@linkplain
812 * #initCause(Throwable) causes} another exception, the first
813 * exception is usually caught and then the second exception is
814 * thrown in response. In contrast, when one exception suppresses
815 * another, two exceptions are thrown in sibling code blocks, such
816 * as in a {@code try} block and in its {@code finally} block, and
817 * control flow can only continue with one exception so the second
818 * is recorded as a suppressed exception of the first.
819 *
820 * @param exception the exception to be added to the list of
821 * suppressed exceptions
822 * @throws NullPointerException if {@code exception} is null
823 * @throws IllegalArgumentException if {@code exception} is this
824 * throwable; a throwable cannot suppress itself.
825 * @since 1.7
826 */
827 public synchronized void addSuppressedException(Throwable exception) {
828 if (exception == null)
829 throw new NullPointerException(NULL_CAUSE_MESSAGE);
830 if (exception == this)
831 throw new IllegalArgumentException("Self-suppression not permitted");
832
833 if (suppressedExceptions == null)
834 suppressedExceptions = new ArrayList<Throwable>();
835 suppressedExceptions.add(exception);
836 }
837
838 private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0];
839
840 /**
841 * Returns an array containing all of the exceptions that were
842 * suppressed, typically by the {@code try}-with-resources
843 * statement, in order to deliver this exception.
844 *
845 * @return an array containing all of the exceptions that were
846 * suppressed to deliver this exception.
847 * @since 1.7
848 */
849 public synchronized Throwable[] getSuppressedExceptions() {
850 if (suppressedExceptions == null)
851 return EMPTY_THROWABLE_ARRAY;
852 else
853 return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY);
854 }
855 }
|
1 /*
2 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
153 */
154 public class Throwable implements Serializable {
155 /** use serialVersionUID from JDK 1.0.2 for interoperability */
156 private static final long serialVersionUID = -3042686055658047285L;
157
158 /**
159 * Native code saves some indication of the stack backtrace in this slot.
160 */
161 private transient Object backtrace;
162
163 /**
164 * Specific details about the Throwable. For example, for
165 * {@code FileNotFoundException}, this contains the name of
166 * the file that could not be found.
167 *
168 * @serial
169 */
170 private String detailMessage;
171
172 /**
173 * A shared value for an empty stack.
174 */
175 private static final StackTraceElement[] EMPTY_STACK = new StackTraceElement[0];
176
177 /*
178 * To allow Throwable objects to be made immutable and safely
179 * reused by the JVM, such as OutOfMemoryErrors, fields of
180 * Throwable that are writable in response to user actions, cause
181 * and suppressedExceptions obey the following protocol:
182 *
183 * 1) The fields are initialized to a non-null sentinel value
184 * which indicates the value has logically not been set.
185 *
186 * 2) Writing a null to the field indicates further writes
187 * are forbidden
188 *
189 * 3) The sentinel value may be replaced with another non-null
190 * value.
191 *
192 * For example, implementations of the HotSpot JVM have
193 * preallocated OutOfMemoryError objects to provide for better
194 * diagnosability of that situation. These objects are created
195 * without calling the constructor for that class and the fields
196 * in question are initialized to null. To support this
197 * capability, any new fields added to Throwable that require
198 * being initialized to a non-null value require a coordinated JVM
199 * change.
200 */
201
202 /**
203 * The throwable that caused this throwable to get thrown, or null if this
204 * throwable was not caused by another throwable, or if the causative
205 * throwable is unknown. If this field is equal to this throwable itself,
206 * it indicates that the cause of this throwable has not yet been
207 * initialized.
208 *
209 * @serial
210 * @since 1.4
211 */
212 private Throwable cause = this;
213
214 /**
215 * The stack trace, as returned by {@link #getStackTrace()}.
216 *
217 * @serial
218 * @since 1.4
219 */
220 private StackTraceElement[] stackTrace;
221
222 // Setting this static field introduces an acceptable
223 // initialization dependency on a few java.util classes.
224 private static final List<Throwable> SUPPRESSED_SENTINEL =
225 Collections.unmodifiableList(new ArrayList<Throwable>(0));
226
227 /**
228 * The list of suppressed exceptions, as returned by {@link
229 * #getSuppressed()}. The list is initialized to a zero-element
230 * unmodifiable sentinel list. When a serialized Throwable is
231 * read in, if the {@code suppressedExceptions} field points to a
232 * zero-element list, the field is reset to the sentinel value.
233 *
234 * @serial
235 * @since 1.7
236 */
237 private List<Throwable> suppressedExceptions = SUPPRESSED_SENTINEL;
238
239 /** Message for trying to suppress a null exception. */
240 private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception.";
241
242 /** Message for trying to suppress oneself. */
243 private static final String SELF_SUPPRESSION_MESSAGE = "Self-suppression not permitted";
244
245 /** Caption for labeling causative exception stack traces */
246 private static final String CAUSE_CAPTION = "Caused by: ";
247
248 /** Caption for labeling suppressed exception stack traces */
249 private static final String SUPPRESSED_CAPTION = "Suppressed: ";
250
251 /**
252 * Constructs a new throwable with {@code null} as its detail message.
253 * The cause is not initialized, and may subsequently be initialized by a
254 * call to {@link #initCause}.
255 *
256 * <p>The {@link #fillInStackTrace()} method is called to initialize
257 * the stack trace data in the newly created throwable.
258 */
259 public Throwable() {
260 fillInStackTrace();
261 }
262
263 /**
264 * Constructs a new throwable with the specified detail message. The
583 */
584 public void printStackTrace(PrintStream s) {
585 printStackTrace(new WrappedPrintStream(s));
586 }
587
588 private void printStackTrace(PrintStreamOrWriter s) {
589 // Guard against malicious overrides of Throwable.equals by
590 // using a Set with identity equality semantics.
591 Set<Throwable> dejaVu =
592 Collections.newSetFromMap(new IdentityHashMap<Throwable, Boolean>());
593 dejaVu.add(this);
594
595 synchronized (s.lock()) {
596 // Print our stack trace
597 s.println(this);
598 StackTraceElement[] trace = getOurStackTrace();
599 for (StackTraceElement traceElement : trace)
600 s.println("\tat " + traceElement);
601
602 // Print suppressed exceptions, if any
603 for (Throwable se : getSuppressed())
604 se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, "\t", dejaVu);
605
606 // Print cause, if any
607 Throwable ourCause = getCause();
608 if (ourCause != null)
609 ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, "", dejaVu);
610 }
611 }
612
613 /**
614 * Print our stack trace as an enclosed exception for the specified
615 * stack trace.
616 */
617 private void printEnclosedStackTrace(PrintStreamOrWriter s,
618 StackTraceElement[] enclosingTrace,
619 String caption,
620 String prefix,
621 Set<Throwable> dejaVu) {
622 assert Thread.holdsLock(s.lock());
623 if (dejaVu.contains(this)) {
624 s.println("\t[CIRCULAR REFERENCE:" + this + "]");
625 } else {
626 dejaVu.add(this);
627 // Compute number of frames in common between this and enclosing trace
628 StackTraceElement[] trace = getOurStackTrace();
629 int m = trace.length - 1;
630 int n = enclosingTrace.length - 1;
631 while (m >= 0 && n >=0 && trace[m].equals(enclosingTrace[n])) {
632 m--; n--;
633 }
634 int framesInCommon = trace.length - 1 - m;
635
636 // Print our stack trace
637 s.println(prefix + caption + this);
638 for (int i = 0; i <= m; i++)
639 s.println(prefix + "\tat " + trace[i]);
640 if (framesInCommon != 0)
641 s.println(prefix + "\t... " + framesInCommon + " more");
642
643 // Print suppressed exceptions, if any
644 for (Throwable se : getSuppressed())
645 se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION,
646 prefix +"\t", dejaVu);
647
648 // Print cause, if any
649 Throwable ourCause = getCause();
650 if (ourCause != null)
651 ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, prefix, dejaVu);
652 }
653 }
654
655 /**
656 * Prints this throwable and its backtrace to the specified
657 * print writer.
658 *
659 * @param s {@code PrintWriter} to use for output
660 * @since JDK1.1
661 */
662 public void printStackTrace(PrintWriter s) {
663 printStackTrace(new WrappedPrintWriter(s));
664 }
791
792 /**
793 * Returns the number of elements in the stack trace (or 0 if the stack
794 * trace is unavailable).
795 *
796 * package-protection for use by SharedSecrets.
797 */
798 native int getStackTraceDepth();
799
800 /**
801 * Returns the specified element of the stack trace.
802 *
803 * package-protection for use by SharedSecrets.
804 *
805 * @param index index of the element to return.
806 * @throws IndexOutOfBoundsException if {@code index < 0 ||
807 * index >= getStackTraceDepth() }
808 */
809 native StackTraceElement getStackTraceElement(int index);
810
811 /**
812 * Read a {@code Throwable} from a stream, enforcing
813 * well-formedness constraints on fields. Null entries and
814 * self-pointers are not allowed in the list of {@code
815 * suppressedExceptions}. Null entries are not allowed for stack
816 * trace elements.
817 *
818 * Note that there are no constraints on the value the {@code
819 * cause} field can hold; both {@code null} and {@code this} are
820 * valid values for the field.
821 */
822 private void readObject(ObjectInputStream s)
823 throws IOException, ClassNotFoundException {
824 s.defaultReadObject(); // read in all fields
825 if (suppressedExceptions != null) {
826 List<Throwable> suppressed = null;
827 if (suppressedExceptions.isEmpty()) {
828 // Use the sentinel for a zero-length list
829 suppressed = SUPPRESSED_SENTINEL;
830 } else { // Copy Throwables to new list
831 suppressed = new ArrayList<Throwable>(1);
832 for (Throwable t : suppressedExceptions) {
833 // Enforce constraints on suppressed exceptions in
834 // case of corrupt or malicious stream.
835 if (t == null)
836 throw new NullPointerException(NULL_CAUSE_MESSAGE);
837 if (t == this)
838 throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
839 suppressed.add(t);
840 }
841 }
842 suppressedExceptions = suppressed;
843 } // else a null suppressedExceptions field remains null
844
845 if (stackTrace != null) {
846 for (StackTraceElement ste : stackTrace) {
847 if (ste == null)
848 throw new NullPointerException("null StackTraceElement in serial stream. ");
849 }
850 } else {
851 // A null stackTrace field in the serial form can result from
852 // an exception serialized without that field in older JDK releases.
853 stackTrace = EMPTY_STACK;
854 }
855
856 }
857
858 /**
859 * Write a {@code Throwable} object to a stream.
860 */
861 private synchronized void writeObject(ObjectOutputStream s)
862 throws IOException {
863 getOurStackTrace(); // Ensure that stackTrace field is initialized.
864 s.defaultWriteObject();
865 }
866
867 /**
868 * Adds the specified exception to the list of exceptions that
869 * were suppressed, typically by the {@code try}-with-resources
870 * statement, in order to deliver this exception.
871 *
872 * If the first exception to be suppressed is {@code null}, that
873 * indicates suppressed exception information will <em>not</em> be
874 * recorded for this exception. Subsequent calls to this method
875 * will not record any suppressed exceptions. Otherwise,
876 * attempting to suppress {@code null} after an exception has
877 * already been successfully suppressed results in a {@code
878 * NullPointerException}.
879 *
880 * <p>Note that when one exception {@linkplain
881 * #initCause(Throwable) causes} another exception, the first
882 * exception is usually caught and then the second exception is
883 * thrown in response. In contrast, when one exception suppresses
884 * another, two exceptions are thrown in sibling code blocks, such
885 * as in a {@code try} block and in its {@code finally} block, and
886 * control flow can only continue with one exception so the second
887 * is recorded as a suppressed exception of the first.
888 *
889 * @param exception the exception to be added to the list of
890 * suppressed exceptions
891 * @throws IllegalArgumentException if {@code exception} is this
892 * throwable; a throwable cannot suppress itself.
893 * @throws NullPointerException if {@code exception} is null and
894 * an exception has already been suppressed by this exception
895 * @since 1.7
896 */
897 public final synchronized void addSuppressed(Throwable exception) {
898 if (exception == this)
899 throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
900
901 if (exception == null) {
902 if (suppressedExceptions == SUPPRESSED_SENTINEL) {
903 suppressedExceptions = null; // No suppression information recorded
904 return;
905 } else
906 throw new NullPointerException(NULL_CAUSE_MESSAGE);
907 } else {
908 assert exception != null && exception != this;
909
910 if (suppressedExceptions == null) // Suppressed exceptions not recorded
911 return;
912
913 if (suppressedExceptions == SUPPRESSED_SENTINEL)
914 suppressedExceptions = new ArrayList<Throwable>(1);
915
916 assert suppressedExceptions != SUPPRESSED_SENTINEL;
917
918 suppressedExceptions.add(exception);
919 }
920 }
921
922 private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0];
923
924 /**
925 * Returns an array containing all of the exceptions that were
926 * suppressed, typically by the {@code try}-with-resources
927 * statement, in order to deliver this exception.
928 *
929 * If no exceptions were suppressed, an empty array is returned.
930 *
931 * @return an array containing all of the exceptions that were
932 * suppressed to deliver this exception.
933 * @since 1.7
934 */
935 public final synchronized Throwable[] getSuppressed() {
936 if (suppressedExceptions == SUPPRESSED_SENTINEL ||
937 suppressedExceptions == null)
938 return EMPTY_THROWABLE_ARRAY;
939 else
940 return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY);
941 }
942 }
|